Ruminant animals, such as beef cattle, are classified as herbivores, meaning they can survive and produce while feeding chiefly on grass or other roughage feed ingredients consisting of large amounts of cellulose. However, cattle which are being produced for slaughter will normally be placed in a confined feeding facility (feedlot) at 7-15 months of age, and fed growing diets consisting of 30-60% roughage and/or finishing diets consisting of only 5-15% roughage (conventional finishing ration), the roughage will normally be in the form of hay, silage, fodder, corn cobs, cottonseed hulls, etc. The remainder of the diet will consist of a high energy grain source such as corn, grain sorghum, barley, wheat, grain by-products, etc., and properly balanced for protein, minerals and vitamins. The roughage ingredients promote average daily gain, by aiding the reduction of incidences of digestive disorders such as loose stools, acidosis, bloat and flounder.
Including 5-15% roughage in the diet of finishing cattle tends to lessen the variation in day-to-day feed intake compared to cattle receiving feed containing no roughage. In addition, roughage in high grain diets stimulates the flow of saliva, which helps buffer the acids produced during fermentation which helps to maintain intake. Although roughage aids in maintaining intake by reducing digestive upsets, the resulting concentration of energy in the diet is reduced. When attempts are made to feed ruminants diets containing no roughage or low amounts of roughage, animal performance is reduced and metabolic problems normally occur. Feed intake of cattle receiving no roughage or low roughage diets becomes very erratic, and the amount of buffering capability through salivation is reduced which leads to rumen malfunction problems.
Without intake behavior modification, normally cattle will tend to consume more of the no roughage or low roughage diet at each feeding and reduce the number of meals each day when compared to a diet with a typical amount of roughage. This erratic intake of all grain (no roughage or low roughage) diets, even though properly balanced for protein and minerals, can result in starch overload which can cause adverse effects to the cattle as well as the profitability of the feedlot. Some adverse effects to profitability include a poorer efficiency of the feed conversion and an increase in the cost to gain ratio.